Method for filtering frying oil

ABSTRACT

An improved apparatus and method for filtering frying oil in a cooker apparatus includes the steps of adding diatomaceous earth to oil in the cooking vessel; draining the oil into a drain pan; drawing the oil through a filter positioned in said drain pan, such that said earth is deposited on the surface of said filter; and returning said oil to the cooking vessel. Thereafter, the oil is filtered by the steps of draining the oil into said drain pan such that the earth is not disturbed to any substantial extent off of the surface of said filter; drawing the oil through said filter; and automatically returning said oil to the cooking vessel. 
     The improved method includes attaching said drain pan and filter to said cooker apparatus and positioning a metallic plate between the drain opening of said vessel and said filter such that the oil drained into said drain pan is initially deflected to prevent disturbing the diatomaceous earth deposited on the surface of said filter.

BACKGROUND OF THE INVENTION

Most prior art oil fryer cooking devices do not include as part of theirstructure means for fully filtering the oil used therein. These devicesrequired that a separate filter apparatus be connected temporarily tothe cooker to provide complete oil filtering using diatomaceous earthfilters or the like. Such diatomaceous earth filters enable the harmfulsolids and other smaller particulate debris in the oil to be removedwhen the oil is drawn through the filter. Disadvantages of such devicesincluded the fact that with a filter separate from the cooker, thefiltering process required that the hot oil be manually handled duringfiltering, a dangerous situation especially for untrained workers.Further, some of the oil is always lost during this process. Finally,the requirements of hooking up the filter apparatus to the cooker addssignificant time to the filtering process, such that it is only normallydone once or twice a day. Thus, the oil is not filtered sufficientlyoften to prevent build-up of impurities and solids, thereby causing theoil to break down and become unusable sooner than would otherwise bepossible.

Other devices have made filters an integral part of the cookerapparatus, but these devices have had the disadvantage that thediatomaceous earth is not used in the filtering process, so that thefilter acts more as a strainer rather than a complete filtering device.Thus only larger particulate matter, e.g. crumbs, are removed by suchfiltering.

Only one other cooker apparatus is known to use diatomaceous earth as anintegral part of its structure. However, this apparatus has the drawbackthat the earth is added to the drain pan, not to the cooking vessel, andit apparently does not include means for preventing the oil fromdisturbing the earth after it has been deposited onto the surface of thefilter during draining of oil into the drain pan. If a portion of thesurface of the filter is exposed, the oil drawn through the filter atthis point is not adequately filtered, thereby reducing theeffectiveness of the filtering operation.

SUMMARY OF THE INVENTION

The present invention eliminates the above identified problems byproviding a method for filtering frying oil wherein the diatomaceousearth is mixed in with the oil while the oil is still in the cookingvessel. The oil is then drained into the drain pan; drawn through thefilter means, including an envelope comprising filter paper or cloth oflow porosity, such that the diatomaceous earth particles are trapped onthe surface of the envelope; and then returned automatically to thecooking vessel. Thereafter, the oil is filtered by draining it into thedrain pan in such a way that the earth on said filter means is notdisturbed thereby. The oil is then drawn through the filter means andthen returned automatically to the cooking vessel.

The improved apparatus includes a stainless steel plate or similarstructure for deflecting the oil as it is drained into the drain pan tothereby prevent the disturbing of the earth deposited on the surface ofsaid filter means.

Therefore, a principal object of the present invention is to provide amethod for filtering frying oil wherein the filter means is an integralpart of the cooker apparatus, and wherein the filter means includes theuse of diatomaceous earth which is not disturbed from the surface of thefilter during the filtering process.

Another object of the present invention is to provide a method forfiltering frying oil wherein the filter is of a simple construction suchthat it is easily and readily assembled and disassembled for cleaningand changing of the filter media and for attachment of the filter anddrain pan to the cooker apparatus.

A still further object of the present invention is to provide anautomatic filtering apparatus, thereby eliminating the manualinteraction of potentially unskilled workers with hot oil during thefiltering process.

Another object of the present invention is to provide a method forfiltering frying oil wherein the amount of oil used up during thefiltering process is substantially reduced over prior filtering devices.

These and other objects and advantages of the present invention willbecome more readily apparent upon reference to the accompanying drawingsand the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a cooker apparatus shown partlybroken away and partly in section, and having a filtering meansaccording to the present invention installed therein.

FIG. 2 is a diagrammatic exploded perspective view of the filter meansused in conjunction with the present invention; and

FIG. 3 is a partly broken away view of the filter means including oildeflection means according to the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

A cooker apparatus having a filtering means according to the presentinvention installed therein is illustrated at 10 in FIG. 1. The cookingapparatus 10 includes a cooking vessel 12 mounted in a suitable housingstructure 14 including a front door 16 and vessel lid 18. The oilnormally retained in vessel 12 is heated by conventional heatingelements 20 which may ring the vessel 12. The bottom of vessel 12includes a drain outlet 22 which is opened or closed by means of a valve24. Valve 24 is controlled in a conventional manner via controls 26located on the front panel 25 of the cooker apparatus.

Positioned beneath outlet 22 is a drain pan 30. A conduit 28 connectedto outlet 22 and valve 24 insures that fluid drained from vessel 12enters drain pan 30. Thus, when valve 24 is opened, the hot cooking oilcontained in vessel 12 drains through outlet 22 into drain pan 30 viaconduit 28.

Positioned along the bottom of drain pan 30 is a filter means 32. A pump36 positioned outside of said drain pan 30 is coupled to the filtermeans 32 by means of a conduit 34. The output of pump 36 is fed tovessel 12 via conduit 38 and return nozzle 40.

An exploded perspective view of the filter means 32 is illustrated inFIG. 2. The filter means 32 comprises a pair of filter screens 40, and42 defined to be positioned operatively adjacent one another such that ahollow chamber 44 is defined therebetween,. A spacer 46 is affixed tofilter screen 42 in a centrally defined position with respect to theedges of said screen. The spacer 46 is of an annular shape having awidth equal to the spacing between the two filter screens 40, 42 whensaid screens are positioned operatively adjacent one another.

A more detailed view of the spacer 46 is shown in FIG. 3, andillustrates the position of the annular portion thereof when the twofilter screens 40, 42 are positioned thereabout. As can be seen, thespacer 46 includes at least one passage 48 extending from said hollowchamber 44 to the hollow interior 50 of said spacer 46. The spacer 46 isfurther defined to include a fastener portion 52 extending axially awayfrom the annular flange portion of said spacer 46. The fastener portion52 is defined to have an open end through which oil is designed to flow.

Referring again to FIG. 2, filter screen 40 is defined to include anopening positioned such that the fastening portion 52 of spacer 46 willextend therethrough when screens 40 and 42 are operatively positionedadjacent one another. A disposable filter element 56 is defined in ashape such that it will envelope screens 40 and 42, such that thesurfaces of said screen plates 40, 42 are enclosed therein. Filterelement 56 also includes a centrally located opening 58 defined in aposition such that fastening portion 52 of spacer 56 will extendtherethrough when filter element 56 is properly positioned about saidscreens 40, 42. Means for fastening the filter element 56 and the screenplates together may comprise clips 60 or other conventional fasteningmeans.

Again referring to FIG. 3, to seal off the hollow chamber 44, acorresponding fastener 62 operatively positioned on conduit 34 is usedto fasten said conduit 34 to spacer 46 by means of fastener portion 52.With fastener 62 tightened onto spacer 46, both filter element 56 andscreen 40 are affixed to said spacer, to prevent oil from leakingthrough the respective openings 58 or 54. Thus, with the pump meansoperating, oil is caused to be drawn through the filter element 56, thefilter screens 40, 42, and into hollow chamber 44. Thereafter, the oilflows through passage 48, hollow interior 50, and into conduit 34. Theoil is ultimately returned to vessel 12 as described above.

FIG. 2 also illustrates that a crumb screen 64 may be provided forcatching larger particulate matter as it flows into the drain pan 30from the vessel 12, to thereby provide preliminary filtering of the oil.This helps prevent the excessive build-up of such particulate matter onthe surface of the filter means 32. The crumb screen 64 may be mountedin a conventional manner in drain pan 30. FIG. 2 illustrates that withan opening 66 defined on said screen 64 in the required position, screen64 may also be attached to spacer 46.

As seen in FIGS. 1 and 2, a key feature of the present invention is theproviding of means for deflecting the oil as the oil is drained intodrain pan 30 from vessel 12. Such means are required to protect thediatomaceous earth which normally exists on the surface of the filtermeans from being disturbed to any substantial extent during saiddraining. In the present embodiment, to provide said means, a stainlesssteel plate 70 is operatively positioned with respect to the surface ofsaid filter means and the outlet opening of conduit 28 such that oildischarged from conduit 28 will strike said plate 70 prior to hittingthe surface of said filter means. In the preferred embodiment, plate 70is rectangular in shape. FIG. 2 illustrates the positioning of plate 70with respect to the crumb screen 64 when such a screen is also a part ofthe present invention.

In operation, after oil has been added to the vessel 12, diatomaceousearth is added thereto and is mixed in to ensure that the earth isdistributed evenly through the oil. Valve 24 is then opened, enablingthe oil to drain into drain pan 30. Since filter element 56 is definedwith a porosity such that the diatomaceous earth is trapped on thesurface thereof, as the oil is drawn through the filter means outthrough spacer 46 and into conduit 34 the earth is caused to coat filterelement 56. The pump means 36 then returns the oil to vessel 12 viaconduit 38 and nozzle 40. The filter means now also includes a thincoating of the diatomaceous earth thereon, as illustrated at 80 in FIG.3.

Thereafter, after the heated oil has been used in the cooking of one ormore batches of food, the oil is filtered to ensure that all particulatematter and impurities are removed therefrom. To provide this periodicfiltering, valve 24 is opened so that the oil is drained into drain pan30 via conduit 28. Metallic plate 70 is positioned such that during thisdraining operation, the oil is deflected so that it does not splashdirectly onto the surface of said filter means. The pump means 36 isthen actuated such that the oil is drawn through said filter means, andtherewith said diatomaceous earth, to thereby filter the oil. The oil isthen returned to vessel 12 via conduits 34 and 38 and nozzle 40. Furthercooking of food is thus enabled to be performed.

Note that it is also contemplated as being within the scope of thepresent invention to have the means for deflecting the oil comprise aplurality of metallic elements positioned on the surface of the filterelement 56. For example, if the oil splashed against conduit 34 as itflowed from conduit 28, a smaller plate 70 may be needed on both sidesof conduit 34.

It is to be understood that the foregoing description is merelyillustrative of a preferred embodiment of the invention and that thescope of the invention is not to be limited thereto but is to bedetermined by the scope of the appended claims.

We claim:
 1. In a deep fat fryer including only one cooking vessel forreceiving cooking oil and food to be cooked; a drain opening at thebottom of said vessel; valve means for opening and closing said drainopening; a removable cover for closing off the top of said vessel; andheater means about said vessel for heating the cooking oil receivedtherein, an improved method for batch filtering said cooking oilcomprising the steps of:(a) adding diatomaceous earth only to the heatedoil in said cooking vessel; (b) opening said valve means and drainingsaid oil into a drain pan, said drain pan including a filter meanspositioned therein having a surface comprising a filter paper envelopeof a porosity designed to trap said earth on said surface; (c) drawingsaid oil through said filter means thereby causing said earth to bedeposited on the surface thereof; (d) returning said oil automaticallyto said vessel; (e) opening said valve means and draining the heated oilinto the drain pan such that said oil is deflected from splashingdirectly onto the surface of said filter means; (f) drawing said oilthrough said filter means thereby filtering said oil; (g) periodicallyreturning said filtered oil automatically to said vessel; and (h)repeating steps (e)-(g).
 2. The method of claim 1, wherein step (e)includes the step of:positioning a metallic sheet on top of said filtersurface directly beneath said drain opening, such that said earth is notdisturbed on said filter surface to any substantial extent duringdraining of said oil into said drain pan.
 3. The method of claim 1,wherein step (f) further comprises the step of:passing said oil througha crumb screen to limit build-up of material on the surface of saidfilter.